introduction pulmonary vein (pv) isolation is considered as a key to atrial fibrillation (af) treatment. cryoballoon ablation is an effective therapy for pv isolation for af with minimal side effects and was approved by the us food and drug administration (fda) several years ago. successful isolation of pvs during cryoablation depends on the balloon temperature and helps in early identification...

Air-to-refrigerant heat exchangers are a key component in all air-conditioning, heat pump and refrigeration systems. The most common of types of air-to-refrigerant heat exchangers are tube-fin and microchannel heat exchangers. There has always been a great emphasis on understating the underlying physics and improving the performance of these heat exchangers. More recently, researchers have been...

Tests were run with both R-12 and R-l34a in a water calorimeter. Refrigerant 12 was run with mineral oil as the lubricant. Evaporating and condensing heat transfer coefficients were calculated over a range of temperatures. To evaluate the impact of the lubricant on the heat transfer coefficients, a oil separator was added. Tests were then run with the oil separator over the same temperature ran...

The world-wide agreement to restrict the use of chlorofluorocarbons (CFCs) and hydrofluorocarbons has prompted recent research exploring the possibilities of replacement refrigerants, particularly those occurring naturally in the environment. One such natural refrigerant, carbon dioxide, has been shown for particular applications to have a COP which is competitive with current refrigerants. How...

Refrigerant mass flow rate is an important measurement for monitoring equipment performance and enabling fault detection and diagnostics. However, a traditional mass flow meter is expensive to purchase and install. A virtual refrigerant mass flow sensor (VRMF) uses a mathematical model to estimate flow rate using low-cost measurements and can potentially be implemented at low cost. This study e...

Hydro-fluorocarbons (HFCs) that are not harmful to ozone layer and used in many appli-cations, including as refrigerants, aerosols, solvents blowing agents for insulating foams replace chlorofluorocarbons hydro (HCFCs). However, some HFCs have a high GWP, which stands “Global Warming Potential(GWP).” Because of the grow-ing concern over global climate change, researchers paying closer attention...

The ability of zeotropic mixtures with a temperature glide to operate in liquid recirculation systems is investigated in this paper, and the preliminary results of an experimental comparison between the performance of R134a and of zeotropic mixture R32/Rl34a, (25/75 by mass) are presented. The perfonnance of Rl34a operating in dry expansion mode are also presented as baseline data. INTRODUCTION...

This paper presents environment friendly refrigerant R290 as a solution to the environmental concerns like depletion of ozone layer and rise in global warming because of wide use of synthetic refrigerants R22 and R134a. The water cooler is the widely used refrigeration application in warm climatic countries. Refrigerant R22 and R134a are predominantly used refrigerants in water cooler refrigera...

This project aims to find correlations between various flow parameters and liquid refrigerant flow distribution within a horizontal manifold supplying two-phase R134a downward into fifteen aluminum microchannels. Liquid flow rates, system pressures, and refrigerant temperatures are recorded. Prior to this project, similar experiments were conducted using an identical manifold setup with water/a...